• Carbon letters
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• v.27
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• pp.90-97
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• 2018

Electromagnetic interference (EMI) shielding is an important issue in modern daily life due to the increasing prevalence of electronic devices and their compact design. This study estimated EMI-shielding effect (EMI-SE) of small ($8-14{\times}17mm$) Hanji (Korean traditional paper) doped with carbon nanotubes (CNTs) and compared to Hanji without CNT using $^2H$ (92.1 MHz) and $^{23}Na$ (158.7 MHz) nuclear magnetic resonance (NMR) peak area data obtained from 1 M NaCl in $D_2O$ samples in capillary tubes that were wrapped in the Hanji samples. The simpler method of using the variation of reflected power and tuning frequency by inserting the sample into an NMR coil was also tested at 242.9, 158.7, and 92.1 MHz. Overall, EMI shielding was relatively more effective at the higher frequencies. Our results validated that NMR methods to be useful to evaluate EMI-SE, particularly for small, flexible shielding materials, and demonstrated that EMI shielding by absorption is dominant in Hanji mixed with CNT.

• Journal of Powder Materials
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• v.25 no.6
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• pp.466-474
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• 2018

The high theoretical energy density ($2600Wh\;kg^{-1}$) of Lithium-sulfur batteries and the high theoretical capacity of elemental sulfur ($1672mAh\;g^{-1}$) attract significant research attention. However, the poor electrical conductivity of sulfur and the polysulfide shuttle effect are chronic problems resulting in low sulfur utilization and poor cycling stability. In this study, we address these problems by coating a polyethylene separator with a layer of activated carbon powder. A lithium-sulfur cell containing the activated carbon powder-coated separator exhibits an initial specific discharge capacity of $1400mAh\;g^{-1}$ at 0.1 C, and retains 63% of the initial capacity after 100 cycles at 0.2 C, whereas the equivalent cell with a bare separator exhibits a $1200mAh\;g^{-1}$ initial specific discharge capacity, and 50% capacity retention under the same conditions. The activated carbon powder-coated separator also enhances the rate capability. These results indicate that the microstructure of the activated carbon powder layer provides space for the sulfur redox reaction and facilitates fast electron transport. Concurrently, the activated carbon powder layer traps and reutilizes any polysulfides dissolved in the electrolyte. The approach presented here provides insights for overcoming the problems associated with lithium-sulfur batteries and promoting their practical use.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.490-495
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• 2012

The catalytic effect induced by activated carbon (AC) was evaluated during the phenol treatment using an ozone/AC ($O_{3}/AC$) process. In the case of the addition of AC to the ozone only process, the decomposition efficiency of dissolved ozone and phenol increased with increasing the amount of AC input. It was that the OH radical generated from the decomposition of dissolved ozone by AC had an effect on the removal of phenol. It was shown as the catalytic effect of AC ([$\Delta$phenol]/$[{\Delta}O_{3}]_{AC}$) in this study. The maximum catalytic effect was approximately 2.13 under 10~40 g/L of AC input. It approached to the maximum catalytic effect after 40 min of reaction with 10 and 20 g/L of AC input, while the reaction time reached to the maximum catalytic effect under 30 and 40 g/L of AC input was approximately 20 min. Moreover, the removal ratios of total organic carbon (TOC) for ozone only process and ozone/AC process were 0.23 and 0.63 respectively.

• Macromolecular Research
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• v.17 no.6
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• pp.430-435
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• 2009

The effect of oxyfluorination temperature on the surface properties of carbon fibers and their reinforced epoxy composites was investigated. Infrared (IR) spectroscopy results for the oxyfluorinated carbon fibers revealed carboxyl/ester (C=O) and hydroxyl (O-H) groups at 1632 and 3450 $cm^{-1}$, respectively, and that the oxyfluorinated carbon fibers had a higher O-H peak intensity than that of the fluorinated ones. X-ray photoelectron spectroscopy (XPS) results indicated that after oxyfluorination, graphitic carbon was the major carbon functional component on the carbon fiber surfaces, while other functional groups present were C-O, C=O, HO-C=O, and $C-F_x$. These components improved the impact properties of oxyfluorinated carbon fibers-reinforced epoxy composites by improving the interfacial adhesion between the carbon fibers and the epoxy matrix resins.

• Korean Journal of Organic Agriculture
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• v.19 no.3
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• pp.291-308
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• 2011

This study was carried out to estimate carbon footprint and to establish of LCA of cherry-tomato production system. I have case study in cultivate cherry tomato (1 kg) calculate in carbon foot print. LCA carried out to estimate carbon foot print and to establish of LCI (life cycle inventory) database of cherry tomato production system. The data is from Research of Farmer's income in 2007 (RDA, 2008), and used Pass (4.1.3) program. The value of fertilizer, amount of pesticide input were show the environmental effect and direct emission. Carbon foot printing in agriculture guarantee the choice right th consumer th choose the row carbon goods. Its can make to strengthen of agriculture and food industry's reduction effort of $CO_2$. Nowadays consumer request food's safety and environment friendly process. Carbon foot printing needs consumer's relief and incentives.

• Korean Journal of Materials Research
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• v.14 no.8
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• pp.565-572
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• 2004

The microstructures of variously heat treated hypoeutectoid($0.45\%$ carbon) and eutectoid($0.85\%$ carbon) steel were characterized by magnetic coercivity measurement. The effect of spheroidization of cementites on the coercivity was investigated for $0.45\%$ carbon steel. In case of $0.85\%$ carbon steel, microstructural parameters such as prior austenite grain size, phase and pearlite interlamellar spacing were measured along with coercivity to investigate the relationships between them. Prior austenite grain size had little effect on the measured coercivity. Coercivity was observed to be high in order of martensite, pearlite and ferrite phases. The linear decrease of coercivity with increasing pearlite interlamellar spacing was found. The effect of each microstructural factor on the coercivity and the potential of coercivity as a nondestructive evaluation parameter for assessing microstructures of steel products are discussed.

• Journal of the Korean Society for Heat Treatment
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• v.10 no.2
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• pp.101-108
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• 1997

In high carbon steels, the cementite phase is more unstable thermally than graphite, and it can lead to a marked deterioration in the formability. Many studies have been carried out to evaluate the effect of the fundamental elements on the graphitization of cementite in high carbon steels. In this present work, the effect of Mn, Cr addition on graphitization in Fe-0.65%C-1.0%Si steel has been investigated by means of hardness testing, optical microscopy and EPMA. The nucleation of graphite may mostly depend on the dissolution rate of cementite into ferrite and the number of the nucleation sites of graphite. The graphitization was promoted by the addition of 0.1%Mn in high carbon steel, but retarded by more addition than 0.5% of Mn. By the more addition of Cr than 0.1%, the graphitization of high carbon steel was strongly retarded. Because Mn was moderate anti-graphitizer, but Cr was stroug anti-graphitizer.

• Carbon letters
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• v.11 no.4
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• pp.325-331
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• 2010

This study investigates the effect of filler content (wt%), presence of interphase and agglomerates on the effective Young's modulus of polypropylene (PP) based nanocomposites reinforced with exfoliated graphite nanoplatelets ($xGnP^{TM}$) and carbon nanotubes (CNTs). The Young's modulus of the composites is determined using tensile testing based on ASTM D638. The reinforcement/polymer interphase is characterized in terms of width and mechanical properties using atomic force microscopy which is also used to investigate the presence and size of agglomerates. It is found that the interphase has an average width of ~30 nm and modulus in the range of 5 to 12 GPa. The Halpin-Tsai micromechanical model is modified to account for the effect of interphase and filler agglomerates and the model predictions for the effective modulus of the composites are compared to the experimental data. The presented results highlight the need of considering various experimentally observed filler characteristics such as agglomerate size and aspect ratio and presence and properties of interphase in the micromechanical models in order to develop better design tools to fabricate multifunctional polymer nanocomposites with engineered properties.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1110-1114
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• 2001

We report the mechanochemical effect of an Fe(NO$_3$)$_3$$.$9H$_2$O-Al(OH)$_3$sample as catalytic precursor mixed-ground by mixer mill on the growth of carbon nanotubes using thermal chemical vapor deposition method. From and TEM observations, carbon products grown on a ground catalyst were more uniform than those grown on an unground catalyst and most of them were identified as carbon nanobubes. Also, it was observed that field emission properties of products on ground catalyst were superior to those of unground catalyst.

• Korean Journal of Metals and Materials
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• v.50 no.10
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• pp.729-734
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• 2012

This study investigated the effect of water absorption on the tensile properties of carbon-glass/epoxy hybrid composites at room temperature and $-30^{\circ}C$. To investigate the effect of the position of glass fabric in the hybrid composite on the tensile properties, the stacking pattern of the fiber fabrics for reinforcing was created in three different ways: (a) glass fabrics sandwiched between carbon fabrics, (b) carbon fabrics sandwiched between glass fabrics and (c) alternative layers of carbon and glass fabrics. They were manufactured by a vacuum-assisted resin transfer molding (VARTM) process. The results showed that there was surprisingly little difference in tensile strength at the two different temperatures with dry and wet conditions. However, the water absorption into the hybrid system affected the tensile properties of the hybrid composites at RT and $-30^{\circ}C$. When the glass fabrics were at the outermost layers, the hybrid composite had the lowest tensile properties. This is attributed to the fact that the composite had a relatively high water absorption rate.